The objectives of the proposed studies involve the evaluation of recognition triggering and effector mechanism against virally determined tumor associated antigens (VDTA). Studies of the effector mechanisms have emphasized antibody dependent, cell mediated cytotoxicity (ADCC) in the Moloney sarcoma virus (MSV) system. Activities of IgM and IgG with specificity for the target cells are being evaluated in terms of their ability to induce cytotoxicity by fractionated lymphocytes. Fractionation of murine lymphocytes include utilization of cell surface markers for T and B cells as well as phagocytosis for removal of macrophages. Also, thymocytes are being fractionated functionally using cortisone acetate treatment in vivo. The structural bases for ADCC are being studied by examining receptors for antigen-antibody complexes on subpopulations of murine lymphocytes. Antigen recognition is being evaluated by testing the influence of antigen-antibody complexes of both the M and G class on the proliferative responses of lymphocytes. Also, to evaluate suppression of lymphocytes triggering (tolerance), neonatal mice are being injected with polyoma transformed cells in graded numbers to determine if these animals will be increasingly susceptible as adults to tumor challenge. We are also extending our studies of the effector mechanisms to the polyoma tumor system.